Reductive and oxidative electrochemical study and spectroscopic properties of nickel(II) complexes with N2O2 Schiff bases derived from (±)-trans-N,N′-bis(salicylidene)-1,2-cyclohexanediamine

Electronic Structure Evaluation of an Oxidized Tris(methoxy)‐Substituted Ni Salen Complex

“…These electrochemical results show that 1 exhibits more accessible redox processes compared with previously studied Ni salen complexes under the same experimental conditions [ ortho ‐ t Bu, and para ‐(NMe 2 , OMe, t Bu); Table 3]. 7d,14 Assuming that all processes are ligand‐based,7x the CV data suggest that each of the phenolate moieties can be oxidized to a phenoxyl radical, and further “ para ‐quinone like” forms due to the ring substitution pattern. Interestingly, the first oxidation process for 1 is similar to that reported for Ni(Sal) t Bu,OMe (Table 3), indicating that the electron‐donating effect of the two substituted phenolates is similar.…”

Aryl‐Aryl Coupling of Salicylic Aldehydes through Oxidative CH‐activation in Nickel Salen Derivatives

“…Oxidation of NiSalens in solution proceeds via three consequent oxidation steps . The potential applied is high enough to ensure the oxidation of the phenolate moiety to the Ni(II)‐phenoxyl radical complex (I oxidation step, E pa (I step) =0.7 – 1.2 V for different Salen‐type complexes) and then the oxidation of the Ni(II)‐phenoxyl radical complex to the Ni(II)‐bis‐phenoxyl radical complex (II oxidation step, E pa (II step) =1.1 – 1.4 V, depending on ligand structure) . Completion of these oxidation steps assures the possibility of the follow‐up reactions (dimerization and polymerization), regardless of the nature of the substituent affecting the reactivity of the radicals, thus making the synthetic protocol most universal.…”

“…Oxidation of NiSalens in solution proceeds via three consequent oxidation steps . The potential applied is high enough to ensure the oxidation of the phenolate moiety to the Ni(II)‐phenoxyl radical complex (I oxidation step, E pa (I step) =0.7 – 1.2 V for different Salen‐type complexes) and then the oxidation of the Ni(II)‐phenoxyl radical complex to the Ni(II)‐bis‐phenoxyl radical complex (II oxidation step, E pa (II step) =1.1 – 1.4 V, depending on ligand structure) .…”

Synthesis, characterization, X-ray crystal structures and antibacterial activities of Schiff base ligands derived from allylamine and their vanadium(IV), cobalt(III), nickel(II), copper(II), zinc(II) and palladium(II) complexes

“…7. Based on literature data recorded for benzene [43] and similar Schiff bases in different solvents [44], all UV spectra of Schiff bases and their complexes exhibit In the Ni(II) and Pd(II) complexes, the band around 400 nm may be due to LMCT (O/N(p)→M(d))…”